Marching Cubes

the performance won't be much different in either case, noise is probably faster. that's got nothing to do with marching cubes though =o

if this is 3d, trilinear interpolation is not a very easy thing. I would suggest you use noise to figure out only if a cube is on or off, then use neighbor checks to see if you are going to cut the cube in half or not. This gets really messy really fast in 3d though. Be sure to consider the asset store unless you're ready to learn a ton over several months of very little progress.